SQLite is only reccomended to be used locally. This forum is using MySQL (MariaDB actually). My impression is that MySQL is more widely used than Postgre, but that people many times prefer Postgre over MySQL. But I do not have the statistics to back it up. I also "believe" REST APIs are more commonly used for applications these days, than connecting directly to a MySQL/Postgre...

When working with MariaDb, you are working with a fork of MySql.
I used to run MySql on a Debian 7 server at work, we're now running Debian 9 servers and they replaced MySql with MariaDB. So, after a simple migration of the data from MySql to MariaDB, our data is now stored in MariaDB.

I didn't need to recode anything in the Gambas applications that work with the database (except for the server name when connecting to the database) as you approach MariaDB exactly the same as MySql (using gb.db.mysql component).

So, you code in Gambas as if you are coding for MySql from a gambas developers point of view.